Journal Article

TNF-α Induces Cytosolic Phospholipase A2 Expression in Human Lung Epithelial Cells via JNK1/2- and p38 MAPK-Dependent AP-1 Activation

Hsiao, Yu-Chun, Cheng, Shin-Ei, Yang, Chuen-Mao, Hsiao, Li-Der, Lee, I-Ta, Lin, Chih-Chung

2013

Overview

Cytosolic phospholipase A2 (cPLA2) plays a pivotal role in mediating agonist-induced arachidonic acid (AA) release for prostaglandin (PG) synthesis during inflammation triggered by tumor necrosis factor-α (TNF-α). However, the mechanisms underlying TNF-α-induced cPLA2 expression in human lung epithelial cells (HPAEpiCs) were not completely understood. We demonstrated that TNF-α induced cPLA2 mRNA and protein expression, promoter activity, and PGE2 secretion in HPAEpiCs. These responses induced by TNF-α were inhibited by pretreatment with the inhibitor of MEK1/2 (PD98059), p38 MAPK (SB202190), JNK1/2 (SP600125), or AP-1 (Tanshinone IIA) and transfection with siRNA of TNFR1, p42, p38, JNK2, c-Jun, c-Fos, or ATF2. We showed that TNF-α markedly stimulated p42/p44 MAPK, p38 MAPK, and JNK1/2 phosphorylation which were attenuated by their respective inhibitors. In addition, TNF-α also stimulated c-Jun and ATF2 phosphorylation which were inhibited by pretreatment with SP600125 and SB202190, respectively, but not PD98059. Furthermore, TNF-α-induced cPLA2 promoter activity was abrogated by transfection with the point-mutated AP-1 cPLA2 construct. Finally, we showed that TNF-α time-dependently induced p300/c-Fos/c-Jun/ATF2 complex formation in HPAEpiCs. On the other hand, TNF-α induced in vivo binding of c-Jun, c-Fos, ATF2, and p300 to the cPLA2 promoter in these cells. In an in vivo study, we found that TNF-α induced leukocyte count in BAL fluid of mice and cPLA2 mRNA levels in lung tissues via MAPKs and AP-1. Taken together, these results demonstrated that TNF-α-induced cPLA2 expression was mediated through p38 MAPK- and JNK1/2-dependent p300/c-Fos/c-Jun/ATF2 complex formation in HPAEpiCs.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Aging / Animal tissues / Arachidonic acid / Arthritis / Asthma / c-Fos protein / c-Jun protein / Cell Line / Chronic obstructive pulmonary disease / Complex formation / Cytokines / Enzymes / Epithelial cells / Epithelial Cells - drug effects / Epithelial Cells - metabolism / Event-related potentials / Gene expression / Group IV Phospholipases A2 - genetics / Group IV Phospholipases A2 - metabolism / Humans / In vivo methods and tests / Inflammation / Kinases / Leukocytes / Lungs / MAP kinase / Medicine / Mitogen-Activated Protein Kinase 8 - genetics / Mitogen-Activated Protein Kinase 8 - metabolism / Mitogen-Activated Protein Kinase 9 - genetics / Mitogen-Activated Protein Kinase 9 - metabolism / mRNA / p38 Mitogen-Activated Protein Kinases - genetics / p38 Mitogen-Activated Protein Kinases - metabolism / Pharmacology / Phospholipase / Phospholipase A2 / Phosphorylation / Physiology / Prostaglandin E2 / Proteins / Secretion / Signal Transduction - drug effects / Signal Transduction - genetics / siRNA / Smooth muscle / Studies / Transcription Factor AP-1 - genetics / Transcription Factor AP-1 - metabolism / Transcription factors / Transfection / Tumor necrosis factor receptors / Tumor Necrosis Factor-alpha - pharmacology / Tumor necrosis factor-TNF / Tumor necrosis factor-α